i would like to confess on this matter...

i have a gf and her bestfrend(a girl) was also my bestfren... the problem hir is that my time on my gf was only a bit unlike to my bestfren, we spend more time and i feel very different when im with my bestfren...should i continue my relationship with my gf??? for me, the thing hir is that i dont want my bestfrend to go away with me and i dont also like my girlfrend to be hurt...